Luminescent quantum dots show promise as tunable, narrow-band light down-converters to complement and replace conventional phosphors. A down-converting quantum dot or phosphor can absorb light of a given wavelength (e.g., blue) and emit light at a longer wavelength (e.g., red). One of the principal limitations of quantum dots as down-converters for lighting and display applications is their instability under conditions of high light flux and/or elevated temperatures, especially in the presence of environmental oxygen and moisture. Exposure to such oxidative and hydrolytic conditions may lead to progressive decomposition of the quantum dot structure, degradation of down-conversion efficiency, and spectral changes in the down-converted light.